This invention relates to an improved wetting agent and its use in the production of edible fat-containing powdered products. More particularly, the invention relates to fat-containing powders that are readily wettable and dispersible in cold aqueous liquids to form reconstituted edible beverages.
Non-fat dry milk products which are readily and completely dispersed in water with little or no agitation to form reconstituted milk have been available for a number of years. Such products are generally made by a process in which spray dried particles of non-fat milk are agglomerated to form porous aggregates, and are commonly referred to as being instantized. Such porous aggregates have high wettability whereby when a quantity of the powder is deposited upon the surface of cold water, the powder mass wets and sinks within a short interval, and disperses upon stirring with a spoon, without the formation of sticky lumps. However, when known methods for the production of instantized non-fat milk are used in the production of products having a substantial fat content, such as whole milk, the resulting product, although in the form of porous aggregates, does not have the desired instant properties. Such dry fat-containing milk products have poor wettability and dispersability in cold water so that the powder tends to float on the surface of water and form sticky lumps upon stirring.
Numerous attempts have been made to improve the wettability and dispersability of such fat-containing milk powders, including the use of wetting agents. Thus, the use of lecithin as a wetting agent to improve the wetting property of fat-containing milk products has been disclosed in the prior art. U.S. Pat. No. 3,120,438 discloses contacting fat-containing milk powder with commercial lecithin by itself or in a corn oil carrier, either by dry blending the ingredients or by spraying lecithin on the milk particles, after which the milk particles are instantized to form porous aggregates. U.S. Pat. No. 3,810,765 discloses adsorbing commercial lecithin on a water soluble sugar and mixing the lecithin-sugar mixture with a fat-containing milk powder. U.S. Pat. No. 3,300,315 discloses the production of instantized fat-containing milk products by subjecting spray dried milk particles to an atmosphere of wet steam having liquid lecithin finely dispersed therein to thereby form porous aggregates having lecithin incorporated thereon. U.S. Pat. No. 3,164,473 discloses the incorporation of liquid lecithin in whole milk powder in a particular manner in order to improve the wettability of the product. For example, anhydrous spray-dried milk powder is passed through a hydrating chamber where it is moistened with water containing lecithin and the moist particles formed into porous aggregates. U.S. Pat. No. 3,291,614 discloses contacting dry fat-containing milk products with lecithin under conditions which distribute the lecithin over the surface of the particles so that all of the fat adjacent the particle surfaces is covered with the lecithin. The lecithin may be applied either as a water emulsion or in a volatile organic solvent such as hexane.
While such prior art procedures purport to improve the wettability and dispersability of fat-containing milk products, they suffer from one or more disadvantages which adversely affect their use in the production of commercial products. For example, reported improvements with respect to wettability and dispersability are usually relative and in few, if any, of the prior art procedures is the final product spontaneously wettable, particularly when reconstituted with cold water. Also, in the prior art procedures, the use of organic solvents or common vegetable oil carriers for the lecithin and/or impurities in the lecithin tends to impart undesirable off-flavors to the product.